Left ventricular outflow tract obstruction after partial atrioventricular septal defect repair

Background. Narrowing of the left ventricular outflow tract has been associ ated with partial atrioventricular septal defect (PAVSD) in about 3% of pat ients. Because of the predisposing anatomy, hemodynamically significant obs truction in the subaortic area may appear after repair of ostium primum atr ial septal defects. Methods. From 1984 to 1998, 40 patients underwent surgical correction of PA VSD by patch closure. The mean age at the initial repair was 5.8 years (ran ge 3 months to 22 years). Results. Nine patients had 12 subsequent operations for hemodynamically sig nificant subaortic obstruction. The mean age at PAVSD repair was 17 months (3 to 42 months) (p < 0.001 compared with others). Follow-up work-up was ob tained due to symptoms in 5 patients and an abnormal echocardiogram in 4 as ymptomatic patients. Subaortic stenosis developed at a mean of 5 years (ran ge 4 months to 10 years), and 6 or more years in 4 patients. The mean age a t subaortic stenosis repair was 6 years (range 2 to 12 years). Nine patient s underwent subaortic fibromuscular resection. Of these, 4 developed recurr ent stenosis and 2 have undergone additional operations. Conclusions. Left ventricular outflow tract obstruction after PAVSD repair may be more frequent than reported. Because of the progressive nature of th e process, echocardiography should be utilized liberally on patients to unc over subclinical stenosis. Long-term follow-up is essential for diagnosis d ue to delayed appearance and lack of reliable clinical signs. (C) 1999 by T he Society of Thoracic Surgeons.